Electric incandescent lamp for projecting purposes



May 19, 1936. D. K. WRIGHT 2,041,583

ELECTRIC INCANDESCENT LAMP FOR PROJECTING PURPOSES Filed June 12, 1934 g Fig.5.

Inventor:

Daniel K.WT-i ht,

H is Attorney Patented May 19, 1936 PATENT OFFICE ELECTRIC INCANDESCENT LAMP FOR PROJECTING PURPOSES Daniel K.'Wrig-ht, Cleveland Heights, Ohio, assignor to General Electric Company, a corporation of New York Application June 12, 1934, Serial No. 730,236

6 Claims. (01; 176-16) '10 so disposed in the bulb that the distance from wall to wall of the bulb in a direction at right angles to the plane of the filament, that'is'yin the direction of maximum light emission,- is less than the distance from wall to wall of the bulb 15 parallel to the plane of the filament. In other words, in an elliptical bulb, the said monoplane filament is preferably disposed symmetrically in the major axis thereof.

One of the advantages of such a bulb is that i it allows the projection equipment to be placed closer to the light source and thus intercept a greater angle of light. Another important advantage is that the dark deposit caused by disintegration of the filament collects on that por- 26 tlon of the bulb which is cooler and where it is least objectionable, that is, at rlght angles to the path of projected light.

One of the features vof my invention is the combination of a bulb having the'shape de- 80 scribed, with a cup-shaped glass body of the type described in my Patent no. 1,967,852, issued July 24, 1934, which has a shape corresponding to that of the bulb and has metal terminal elements sealed thereto. a

v5 Further features and advantages of my invention will appear from the following detailed descrlption of species thereof and from the drawing. -In the drawing. Fig. 1 is a front elevation of an incandescent projection lamp comprising my in: vention; Fig. 2 is a section through the line 2-2 of Fig. 1: Fig. 3 is a front elevation of a'modiiied lamp; and Fig. 4 is a section through the line 4-4 of Fig. 3.

Referring to Figs. 1 and 2, the lamp comprises a cylindrical bulb ll of substantially elliptical or oval cross-section. The end of said bulb I8 is sealed to .the edge of a cup-shaped pressed glass body ll of the type disclosed in my patent referred to above, which is also elliptical in cross- 50 section and has depending hollow tube or legportions 12 to which are sealed the ends of thimble-shaped metal'terminal elements II. The ends of a monoplane filament M are connected to'rigid leads l5 which are preferably channel shaped and extend into the metal thimbles I! to which they are securely fastened. The filament is supported by wires l6 and Il which are mounted on insulating blocks l8, 19. The bulb is exhausted and preferably filled with an inert gas and then tipped-off at 20. The black 5 deposit of filamentary material will collect along the elongated sides of the bulb which are cooler than the front and back and where it is least objectionable since it is at right angles to the path of projected light. 10

In the modified lamp shown in Figs. 3 and 4, the filament 2| is located in a comparatively small elliptical or oval portion 22 at the tip or end of the main body portion 23 of the bulb which may be cylindrical in cross-section. The cupshaped pressed glass body 24 in this case is, of course,-cylindrical in cross-section. The elliptical end portion 22 0f the bulb is preferably made of a glass which has a higher softening point than the body portion 23' of the bulb. This type of construction makes possible a still greater concentration of the projection system.

What I claim as new and desire to secure by Letters Patent of the United States is:

-l. An incandescent projection lamp compris- 25 ing a bulb having a reduced portion at one end thereof and a filament disposed in said reduced end portion and so designed that the light rays emanating therefrom will be at a maximum in a 'givemdir'ection, the said reduced end portion of said'bulb having a cross-section of such shape that the distance from wall to wall thereof in the direction of maximum light emission is less than the distance. from wall to wall at'right angles to the said direction of maximum light emission.

2. An incandescent projection lamp comprising a bulb having a reduced portion of substantially elliptical cross-section at one .end thereof and a monoplane filament disposed in said elliptical reduced end portion substantially in the major axis 40 threof.-

3. A high intensity projection lamp comprising an axially elongated bulb, the distance from the front to the back wall of said bulb in a direction at right anglesto said axis being substantially collects on said sidewalls.

4. A high intensity projectionimp comprising 5i! a, substantially cylindroidal bulb, and a filament in said bulb designed so that the light rays emabulb at the ends of the said major axis being cooler during the operation of the lamp than the walls in the direction of maximum light emission whereby the dark deposit caused by evaporation of the filament collects on said sidewalls.

5. A high intensity projection lamp comprising a substantially cylindroidal bulb having a monoplane filament therein, the said filament being disposed substantially symmetrically in the longitudinal axis of the bulb and in the major axis of the elliptical cross-section of the bulb, the sidewalls of said bulb at the ends of the saidmaior axis being cooler during the operation of the lamp than the walls at right angles thereto whereby the dark'deposit caused by evaporation of the filament collects on said sidewalls.

6. A high intensity projection lamp comprising a cup-shaped body of substantially elliptical cross-section having a pair of outwardly extending metal terminal elements sealed to the bottom thereof, a substantially cylindroidal bulb sealed at one end to the rim of said elliptical body, a pair of leads extending into said bulb from said terminal elements, and a filament mounted on said leads and so designed that the maximum light emission therefrom is at right angles to the major axis. of the elliptical cross-section of said 3 bulb.

DANIEL K. WRIGHT. 

